It is the objective of this project to develop and obtain microwave exposure systems for bioeffects research and to develop and test techniques for measuring energy absorption. Waveguide systems for exposing cell preparations, which allow stirring during exposure have been developed. These systems also have the capability of controlling temperature at any desired level between 10 degrees C and 60 degrees C. The systems operate at 2450 MHz and are capable of providing specific absorption rates (SAR's) from 0 to 100 mW/g using continuous wave radiation and 0-30 mW/g using pulse wave radiation. These systems have been modified further so that analytical on-line monitoring of biological parameters can be performed. Techniques which can now be used in detecting biological changes include circular dichroism and fluorescence. A circularly polarized waveguide system for long-term studies has been obtained and is being calibrated.